City-sized iceberg drifts into ocean

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(CNN) -- A massive iceberg with an area almost twice the size of Atlanta is moving into the ocean off Antarctica and could threaten shipping during the Antarctic winter, scientists say.

The ice island, known as iceberg B31, covers 255 square miles and could be almost a third of a mile thick, scientists say in a report from NASA's Earth Observatory.

The iceberg calved from Antarctica's Pine Island Glacier last November, according to NASA. The crack that produced it was first spotted in 2011.

Since November, B31 has drifted out of Pine Island Bay and into the Amundsen Sea off the western side of the continent.

http://www.cnn.com/2014/04/22/world/asia/antarctic-iceberg/index.html?hpt=hp_t1